Project description:Chromatin insulators are DNA protein complexes that mediate inter and intra chromosomal interactions. Boundary Element Associated Factor- 32 (BEAF-32) is an insulator protein predominantly found near gene promoters and thought to play a role in gene expression. We find that mutations in BEAF-32 are lethal, show loss of epithelial morphology in imaginal discs and cause neoplastic growth defects. To investigate the molecular mechanisms underlying this phenotype, we carried out a genome-wide analysis of BEAF-32 localization in wing imaginal disc cells. Mutation of BEAF-32 results in miss-regulation of 3850 genes by at least 1.5-fold, 647 of which are bound by this protein in wing imaginal cells. Up-regulated genes encode proteins such as Bazooka, a determinant of cell polarity; the Insulin receptor-1 and the p70-S6 kinase, involved in the insulin growth factor pathway that can activate various pathways involved in cell proliferation; and the Unpaired 3 ligand of the Janus kinase (JNK) pathway, and its target gene Socs35, which can also activate cell proliferation. The expression of genes involved in DNA homologous end repair and oxidative stress pathways is also increased in BEAF-32 mutants. Among the down-regulated genes are those encoding components of the Wingless pathway, which is required for cell differentiation, and amino acid metabolism. Miss-regulation of these genes explains the unregulated cell growth and neoplastic phenotypes observed in imaginal tissues of BEAF-32 mutants. Here we examine mapping the genomic binding sites and its distribution of BEAF-32, a Drosophila insulator proteins in wing imaginal tissue. We performed ChIP-seq analysis using BEAF-32B.
Project description:Chromatin insulators are DNA protein complexes that mediate inter and intra chromosomal interactions. Boundary Element Associated Factor- 32 (BEAF-32) is an insulator protein predominantly found near gene promoters and thought to play a role in gene expression. We find that mutations in BEAF-32 are lethal, show loss of epithelial morphology in imaginal discs and cause neoplastic growth defects. To investigate the molecular mechanisms underlying this phenotype, we carried out a genome-wide analysis of BEAF-32 localization in wing imaginal disc cells. Mutation of BEAF-32 results in miss-regulation of 3850 genes by at least 1.5-fold, 647 of which are bound by this protein in wing imaginal cells. Up-regulated genes encode proteins such as Bazooka, a determinant of cell polarity; the Insulin receptor-1 and the p70-S6 kinase, involved in the insulin growth factor pathway that can activate various pathways involved in cell proliferation; and the Unpaired 3 ligand of the Janus kinase (JNK) pathway, and its target gene Socs35, which can also activate cell proliferation. The expression of genes involved in DNA homologous end repair and oxidative stress pathways is also increased in BEAF-32 mutants. Among the down-regulated genes are those encoding components of the Wingless pathway, which is required for cell differentiation, and amino acid metabolism. Miss-regulation of these genes explains the unregulated cell growth and neoplastic phenotypes observed in imaginal tissues of BEAF-32 mutants.
Project description:Insulators are DNA sequences that control the interactions among genomic regulatory elements and act as chromatin boundaries. A thorough understanding of their location and function is necessary to address the complexities of metazoan gene regulation. We studied by ChIP-chip the genome-wide binding sites of 6 insulator-associated proteins – dCTCF, CP190, BEAF-32, Su(Hw), Mod(mdg4) and GAF – to obtain the first comprehensive map of insulator elements in Drosophila embryos. We identify over 14,000 putative insulators, including all previously known insulators. We find two major classes of insulators defined by dCTCF/CP190/BEAF-32 and Su(Hw) respectively. Distributional analyses of insulators revealed that particular sub-classes of insulator elements are excluded between cis-regulatory elements and their target promoters, divide differentially expressed, alternative, and divergent promoters, act as chromatin boundaries, are associated with chromosomal breakpoints among species, and are embedded within active chromatin domains. Together, these results provide a map demarcating the boundaries of gene regulatory units, and a framework for understanding insulator function during the development and evolution of Drosophila. For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf
Project description:Specific interactions of the genome with the nuclear lamina (NL) are thought to assist chromosome folding inside the nucleus and to contribute to the regulation of gene expression. High-resolution mapping has recently identified hundreds of large, sharply defined lamina-associated domains (LADs) in the human genome, and suggested that the insulator protein CTCF may help to demarcate these domains. Here, we report the detailed structure of LADs in Drosophila cells, and investigate the putative roles of five insulator proteins in LAD organization. We found that of these five proteins, only SU(HW) binds preferentially at LAD borders and at specific positions inside LADs, while GAF, CTCF, BEAF-32 and DWG are mostly absent from these regions. By knockdown and overexpression studies we demonstrate that SU(HW) weakens LAD – NL interactions by a local antagonistic effect. Our results provide insights into the evolution of LAD organization and reveal a role for SU(HW) in the regulation of genome – NL interactions. DamID experiments for Lamin, CTCF, SU(HW), GAF, DWG, and BEAF-32, and for Lamin after overexpression and after knockdown of SU(HW), were performed in Drosophila cell cultures. Samples were hybridized to 380k NimbleGen arrays with 300 bp probe spacing. Every experiment was done in duplicate in the reverse dye orientation. The supplementary file 'GSE20311_DamID_norm_mean.txt' contains the mean log2(Dam-fusion/Dam-only) values of two replicates.
Project description:Specific interactions of the genome with the nuclear lamina (NL) are thought to assist chromosome folding inside the nucleus and to contribute to the regulation of gene expression. High-resolution mapping has recently identified hundreds of large, sharply defined lamina-associated domains (LADs) in the human genome, and suggested that the insulator protein CTCF may help to demarcate these domains. Here, we report the detailed structure of LADs in Drosophila cells, and investigate the putative roles of five insulator proteins in LAD organization. We found that of these five proteins, only SU(HW) binds preferentially at LAD borders and at specific positions inside LADs, while GAF, CTCF, BEAF-32 and DWG are mostly absent from these regions. By knockdown and overexpression studies we demonstrate that SU(HW) weakens LAD – NL interactions by a local antagonistic effect. Our results provide insights into the evolution of LAD organization and reveal a role for SU(HW) in the regulation of genome – NL interactions.
Project description:Specific interactions of the genome with the nuclear lamina (NL) are thought to assist chromosome folding inside the nucleus and to contribute to the regulation of gene expression. High-resolution mapping has recently identified hundreds of large, sharply defined lamina-associated domains (LADs) in the human genome, and suggested that the insulator protein CTCF may help to demarcate these domains. Here, we report the detailed structure of LADs in Drosophila cells, and investigate the putative roles of five insulator proteins in LAD organization. We found that of these five proteins, only SU(HW) binds preferentially at LAD borders and at specific positions inside LADs, while GAF, CTCF, BEAF-32 and DWG are mostly absent from these regions. By knockdown and overexpression studies we demonstrate that SU(HW) weakens LAD – NL interactions by a local antagonistic effect. Our results provide insights into the evolution of LAD organization and reveal a role for SU(HW) in the regulation of genome – NL interactions.